Factories that use water during manufacturing processes often produce effluents or wastewater streams that may be unacceptably high in organic contaminants. In particular, paper mills mix water with wood pulp as part of paper manufacturing processes. The resulting effluent or wastewater stream from the mill may include refractory organics and will have a noticeably brown color. There is a need to substantially remove suspended solids and the color from the effluent and to detoxify certain refractory organics.
Various filters are employed in the effluent streams from paper mills and other manufacturing facilities to remove suspended solids from the stream. These prior art filters often will not sufficiently remove color from the effluent stream. In particular, it is desired to remove at least 80% of the color from the effluent stream from a paper mill.
The prior art has attempted to employ hydrogen peroxide, ozone and/or ultraviolet light to oxidize refractory organics in aqueous water streams. For example, U.S. Pat. No. 4,012,321 which issued to Koubek on Mar. 15, 1977 shows a method wherein a predetermined amount of hydrogen peroxide is added under pressure to an aqueous waste stream. The hydrogen peroxide and the aqueous waste stream is thoroughly mixed by an in-line mixer or agitator, and the resultant mixture is subsequently irradiated under ultraviolet light at a wave length no greater than 260 nm.
A similar teaching is shown in U.S. Pat. No. 4,289,728 which issued to Peer et al. on Sep. 15, 1981. U.S. Pat. No. 4,289,728 discloses a method of sterilization in which microorganisms are treated with an ultraviolet irradiated solution of hydrogen peroxide. The method of U.S. Pat. No. 4,289,728 is particularly directed to the sterilization of surfaces of containers. The surfaces are treated with a hydrogen peroxide solution at an elevated temperature, for example, by passing the container through a tank containing the solution or by spraying the walls of the container with the solution. When the container emerges from the hydrogen peroxide treatment, it is then irradiated by ultraviolet light at a wavelength no greater than 325 nm.
Ultrox International of Santa Ana, Calif. has received grants from the State of California, Department of Health Services to study the oxidation of organic contaminants in ground water. Ultrox International reported to the State of California in Mar. 1989 on a process where wastewater was treated with ozone and UV irradiation or with hydrogen peroxide and UV irradiation. The Ultrox report to the State of California clearly illustrated that hydrogen peroxide was added to the ground water being treated before injection of the resulting admixture into a UV reactor. The Ultrox reports to California assert that the hydrogen peroxide, ozone and UV irradiation treatments disclosed therein may generate hydroxyl radicals.
Certain of the Ultrox work is disclosed in patents. In particular, U.S. Pat. No. 4,780,287 issued to Zeff et al. on Oct. 25, 1988. U.S. Pat. No. 4,780,287 is directed to an apparatus containing porous adsorbent beds comprising quartz chips or silica gel wherein contaminated solutions are exposed to ozone and UV irradiation. The disclosure also refers to hydrogen peroxide addition to the contaminated solution prior to injection into the UV reactor.
Ultrox also owns U.S. Pat. No. 4,792,407 which issued to Zeff et al. on Dec. 2, 1987. This reference discloses exposure of ground water to ozone, hydrogen peroxide and UV irradiation.
Ultrox's U.S. Pat. No. 4,849,114 issued on Jul. 18, 1989 and includes a similar disclosure to the above referenced U.S. Pat. No. 4,792,407. However, U.S. Pat. No. 4,849,114 is specifically directed to oxidizing hydrazine and hydrazine derivatives.
It is desired to provide a method and apparatus for decolorization of an effluent stream, and in particular an effluent stream from a paper mill. More particularly, it is desired to provide an apparatus and process for more effectively reducing color of a wastewater effluent stream than is provided by the prior art.
Accordingly, it is an object of the subject invention to provide a method and apparatus for substantially removing color from an effluent stream, and preferably for removing at least 80% of the color.